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Question 186-1 : The latitude of the tropic of capricorn is ? [ Question security ]
23,5°s.
Question 186-2 : Which statement is true ?
The declination of the sun and the latitude of the observer will affect the duration of civil twilight.
Question 186-3 : At 00h00 local mean time of an observer ?
The mean sun is in transit with the observer's anti meridian.
.local mean time is solar time as measured by the position of the mean sun with respect to an observer's local meridian. local mean time differs continuously with the observer's longitude and is not standardized over a time zone. however, a day as measured by local mean time does not vary in length throughout the year, it is always 24 hours and at midnight 00h00 it will be on the observer's anti meridian.
Question 186-4 : Kepler's second law states that ?
The radius vector sun earth sweeps out equal areas in equal time.
Question 186-5 : Consider the positions 00°n/s, 000°e/w and 00°n/s, 180°e/w on the ellipsoid. which statement about the distances between these positions is correct ?
The route via the north pole is shorter than the route along the equator.
.since earth shape is an ellipsoid, the distance from position a 00°n/s, 000°e/w to b 00°n/s, 180°e/w , both located on the equator, will be shorter via the poles... /com en/com061 587.jpg..
Question 186-6 : The sr/ss sunrise/sunset table for the 23rd of february at latitude 40°n gives.sr = 06 44.ss = 17 44.at 12 00 central european time utc+1 at 40°n ?
The sun rises at 64°w.
.sr and ss are given in utc, so we need to know first the central european time in utc..when it is 11 00 utc, it's 12 00 local time in central europe utc+1....now, in central europe, the sun rises at 06h44 utc, so, 4h and 16 minutes later at 11 00utc , where does the sun is rising..answer we must be near the north american and canadian border, close to the coast....4h and 16 minutes = 256 minutes...what is the speed of the trace of the sunrise on the ground...1440 minutes per day 24h per day , 360° to cover for a complete turn of the sun around the earth, so 1440/360 = 4 minutes par degree...256/4 = 64°...when it is 11 00 utc, the sun rises at 64° west of our position.
Question 186-7 : An aircraft follows a great circle in the northern hemisphere. at a certain moment the aircraft is in the position on the great circle where the great circle direction is 270° t. continuing on the great circle the ?
Track angle will decrease and the latitude will decrease.
. /com en/com061 594.jpg..following a great circle track in the northern hemisphere, your heading will decrease track angle will decrease and the latitude will decrease too.
Question 186-8 : On an oblate spheroid representing the earth's shape ?
1 minute of arc along the equator measures a greater distance than 1 minute of arc along the meridian at a latitude of 45°n/s.
.the earth is a tad wider than it is tall, giving it a slight bulge at the equator. this shape is known as an ellipsoid. the diameter from the north pole to the south pole the shortest diameter is approximately 6860 nm and the equatorial diameter the longest diameter is approximately 6883 nm..the polar circumference is 21554 nm, each minute of arc being equal to 0.998 nm..the equatorial circumference is 21626 nm, each minute of arc being equal to 1.001 nm.
Question 186-9 : Given.a 56°n , 145°e.b 57°n , 165°w.what is the difference in longitude between a and b ?
050°.
.we only want to know the difference in longitude between a and b is 50°, not the distance between a and b so latitudes are irrelevant...from a longitude, to reach the anti meridian 180°e/w , we have 35° of longitude, and then, to reach b longitude, we have 15° of longitude..35° + 15° = 50°.
Question 186-10 : What is the duration of morning civil twilight at 66°48'n, 095°26'w on 27th of january. 2480 ?
01h 13m.
. 1809.at 67°n, on january 26th, the duration of morning civil twilight is 1h34 min...we are looking for january 27th.you can continue to interpolate with january 28th but if you look at the sunrise difference time between 26th and 28th at 66°n, you gain 11 minutes. now for the morning civil twilight, between 26th and 28th at 66°n, you gain 7 minutes..so for january 27 th, 1h33 minutes sounds good.
Question 186-11 : The gmt of morning civil twilight at 66°48'n, 095°26'w on 27th of january is.. err a 061 605 ?
1436 gmt.
.the answers are all in gmt, so take the time from the annex, and adjust for longitude at 15°/h.95°26' / 15 = 6h 22min...as the location is west of the prime meridian, the answer must be later in the day reference to gmt.0814 + 6 hrs 22 = 1436 gmt... notice 0814 is calculated by interpolation.
Question 186-12 : The gmt of sunrise at 66°48'n, 095°26'w on 27th of january is.. err a 061 606 ?
1549 gmt
.sunrise at 66°48'n, 095°26'w on 27th of january.. /com en/com061 606.jpg...interpolation between 26th and 29th january. difference at 68n is 13 minutes for 4 days, so for one day is 3.25 minutes.. difference at 66n is 11 minutes for 4 days, so for one day is 2.75 minutes...we are looking for 66°48'n, 3 minutes is a good deal....09h39 66°n to 9h45 68°n on january 26th at 66°48' it will be 09h32 and 09h49 on january 27th....now, convert local mean time lmt at longitude 095°26'w.95.4° x 4 minutes = 381.6 minutes..381.6 minutes = 6.36 hours = 6 h 22 minutes...09h49 + 6h42 = 15h51 utc.
Question 186-13 : The latitude of the tropic of cancer is ?
23,5°n.
Question 186-14 : Position a is 31°00's, 176°17'w.rhumb line track t from a to b is 270°..initial great circle track t from a to b is 266.2°..the approximate position of b is ?
31°00's, 168°58'e
.difference between the great circle track and rhumb line track is conversion angle...conversion angle = 270° 266.2° = 3.8°..1/2g sin 31° = 3.8°.g change of longitude.1/2g = 3.8° / sin 31°.1/2g = 7.38°.g = 14.76°...176°17'w + 14.76° or 14°45' = 168°58'est.
Question 186-15 : An aircraft departs from schiphol airport and flies to santa cruz in bolivia south america via miami in florida..the departure time off blocks is 07h45 st utc + 1 at the 10th of november, taxi time before take off at schiphol is 25 minutes. the flight time to miami over the atlantic ocean is 09h40m. ?
21h05 10th nov.
Cmarzocchini.i only did 06h45 utc off blocks + 00h45 + 09h40 + 00h45 + 02h40 + 06h30 = 26h05..in santa cruz bolivia utc +5, so, 26h05 5h = 21h05 same day.
Question 186-16 : Two places on the parallel of 47°s lie 757.8 km apart. calculate the difference in longitude ?
10°00'.
.first convert km in nm..757.8 km / 1.852 = 409 nm...distance = change of longitude x cos of latitude..409 nm = change of longitude x cos 47°..change of longitude = 409 / cos 47° = 600 minutes..600 / 60 min per degree = 10°.
Question 186-17 : In a sunrise/sunset table given for the 28th of june at a certain latitude, sunrise is gven as 0239 and sunset is given as 2127..what is the latitude ?
60°n.
.it must be in the northern hemisphere, because it's summer and 28th of june. it's quite a long period of daylight, but at 80 degrees north you have mid summer night. this is where the sun never goes below the horizon. i think that's why the answer is 60 degrees north... .absolutly, we are close to the longest day during summer time in the northern hemisphere..furthermore, above 66.5°n, in summer, it is permanent daylight.
Question 186-18 : On the earth's ellipsoid one degree of latitude near the equator is ?
Less than 60 nm.
.at the equator, one degree of latitude = 110.57 km or 59.7 nm...at 50°n or 50°s, one degree of latitude = 111.23 km or 60.05 nm...at the poles, one degree of latitude = 111.69 km or 60.3 nm...the geoid is an ellipsoidal form, so a degree of latitude centered on the equator is not the same length as one degree of longitude along the equator. the difference is small enough to ignore for many applications.
Question 186-19 : With an increase in magnetic latitude there will be a decrease in the ?
Directive force.
.the directive force is the horizontal component of the earth's magnetic field. the horizontal component of the earth's magnetic field is stronger at magnetic equator and very weak at the magnetic poles..thus, if you are heading to the magnetic poles your latitude is increasing there will be a decrease in the directive force.
Question 186-20 : Which statement about the duration of daylight is true ?
Close to the equinoxes the influence of latitude on the duration of daylight is at its smallest.
Question 186-21 : Which figure in the appendix represents the geocentric latitude of position p, which is situated above the surface of the ellipsoid.. err a 061 662 ?
Figure b.
.geocentric latitude is measured from the centre of the ellipsoid. geodetic or geographic latitude which is what is normally measured is the angle between the plane of the equator and the line, which is normal to the ellipsoid at the point of interest. unlike geocentric latitude, this line does not typically pass through the centre of the ellipsoid. whenever the unqualified term latitude is used, it will normally mean the geographic latitude... /com en/com061 662.jpg..on the wgs84 ellipsoid, the length of a degree of latitude increases from 110.574 km at the equator to 111.694 km at the poles. geographic and geocentric latitudes can differ by as much as 12 minutes of arc, an amount equivalent to a distance of more than 30 km on the ground.
Question 186-22 : Which figure in the appendix represents the geographic latitude of position p, which is situated above the surface of the ellipsoid.. err a 061 663 ?
Figure a.
.geographic latitude is define as the angle between the plane of the equator and the local plumb line on the ellipsoid..on figure a, you can notice that the local plumb line intersects the plane of the equator not in the center of the sphere, because earth is an ellipsoid.
Question 186-23 : The long term periodic change in the earth's magnetic field ?
Is reflected in the slow movement of the magnetic poles.
Feedback pour traduction fr 'a quoi est dûe la variation du champ magnétique terrestre au déplacement lent et progressif des pôles magnétiques'
Question 186-24 : The horizontal component of the earth's magnetic field ?
Is very small close to the magnetic poles.
. /com en/com061 593.jpg..diagrammatic representation of the earth's magnetic field illustrating how field lines represented by arrows intersect the earth's surface, and how inclination angle the angle formed between the field lines and the earth varies with latitude. at the magnetic equator the curving line across the earth , field lines are parallel to the earth's surface. the field lines become progressively steeper as one travels north toward the magnetic pole, where the field lines are directed straight down into the earth and the inclination angle is 90°.. near the magnetic pole the horizontal component of the earth's magnetic field is too small to permit the use of a magnetic compass.
Question 186-25 : An observer is situated on the parallel of 23.5°s. which statement about the passage of the apparent sun in relation to this position is correct ?
It passes through the zenith once a year around december 22nd.
Question 186-26 : At 54°n, 020°w the sun rises on november 28th at 09 01 utc..at 44°n, 020°w the sun will rise ?
Earlier since the latter position lies further south.
.on november 28th, we are approaching winter solstice 21 22 december.. 1781.the axis of the earth is tilted 23.5° degrees from 'vertical'. this causes the northern hemisphere to be tilted toward the sun during half the year, and tilted away from the sun the other half of the year..after autumnal equinox, northern hemisphere is tilted away and, as you can see on this picture, position '44°n 020°w' will see the sun rising earlier than the position '54°n 020°w'.
Question 186-27 : What is the correct definition of latitude of a position on the earth ?
Latitude is the angle between the plane of the equator and the line from the centre of the earth to the position.
Question 186-28 : When proceeding, on a given date, along a parallel towards the east, the moment of sunrise will occur one hour earlier every 15° difference in longitude when it is expressed in ?
Utc
Question 186-29 : The maximum difference in distance when proceeding along the great circle between two positions, in stead of the rhumb line, will occur ?
On east west tracks at high latitudes.
Img /com en/com061 674.jpg..green great circle track.red rhumb line..right answer is east west track at high latitudes but west east track at high latitudes will also be right.
Question 186-30 : Geodetic latitude and geocentric latitude coincide ?
At the poles and on the equator.
Question 186-31 : The time difference in local mean time between sunset at positions a 50°n, 120°e and b 50°s, 120°e on the 21st of november is ?
Some hours and the sun rises earlier in b than in a.
.on the 21st of november, it's winter in northern hemisphere..timing of sunsets and sunrises are driven by the axial tilt of earth, in the summertime, the days get longer and sunsets occur later..thus, since it is summer in southern hemisphere, the sun will rise earlier in b than a, and the sun will disappear earlier in a than in b.
Question 186-32 : Which statement about standard time is true ?
Standard time is determined by the government of the appropriate state and does not necessarily follow the borders of 15° wide longitude zones.
.the local time at 125°w is utc 8h40m. the standard time is determined by the government of the appropriate state and does not necessarily follow the borders of 15° wide longitude zones.
Question 186-33 : Which statement is correct about the apparent solar day ?
The apparent solar day is the period between two successive transits of the true sun through the same meridian.
Question 186-34 : Which statement regarding the apparent sun and the mean sun is correct ?
The apparent sun is the visible sun, the mean sun is a fictitious sun.
.apparent sun 'apparent solar time' or 'true solar time' is given by the daily apparent motion of the true, or observed, sun. it is based on the apparent solar day, which is the interval between two successive returns of the sun to the local meridian...the mean sun is imaginary sun moving along the celestial equator at a constant rate and completing its annual course in the same time as the sun takes to move round the ecliptic at a varying rate. it is used in the measurement of mean solar time...mean solar time conceptually is the hour angle of the fictitious mean sun. the duration of daylight varies during the year the length of a mean solar day is nearly constant, unlike that of an apparent solar day.
Question 186-35 : The declination of the sun is defined as ?
The angular distance of the sun north or south of the celestial equator.
. /com en/com061 682.gif..directly above the equator of the earth we find the celestial equator in the sky...declination of the sun is the angular distance of the sun north or south of the celestial equator.. /com en/com061 682a.jpg..the earth's equator is tilted 23.5 degrees with respect to the plane of the earth's orbit around the sun, so at various times during the year, as the earth orbits the sun, declination varies from 23.5 degrees north to 23.5 degrees south.. /com en/com061 682b.jpg..this gives rise to the seasons. around december 21, the northern hemisphere of the earth is tilted 23.5 degrees away from the sun, which is the winter solstice for the northern hemisphere and the summer solstice for the southern hemisphere. around june 21, the southern hemisphere is tilted 23.5 degrees away from the sun, which is the summer solstice for the northern hemisphere and winter solstice for the southern hemisphere. on march 21 and september 21 are the fall and spring equinoxes when the sun is passing directly over the equator. note that the tropics of cancer and capricorn mark the maximum declination of the sun in each hemisphere.
Question 186-36 : The time interval between sunrise and sunset is dependent on ?
The declination of the sun and the latitude of the observer.
.depending on your location, the times of sunrise and sunset, and the length of the daylight period, varies in a sine wave pattern..the axis of spin of the earth is not vertical to the plane between the earth and the sun..even though the earth spins on that axis, and rotates around the sun, the tilt of the axis never changes. because of this, the northern and southern hemispheres are exposed to more or less sunlight at different times..as a result, when the top of the earth is in a position where it is closer to the sun, the sun's light rays strike well above the equator, resulting in summer, and longer days.. /com en/com061 684.gif.when it is summer in the northern hemisphere, it is winter in the southern hemisphere.
Question 186-37 : The definition of true north for any observer is ?
The direction of the observer's meridian to the north pole.
.true north may, in practical terms, be magnetic north corrected for local variation but that is not the definition. the definition is 'the direction from the observer to the geographic north pole, along the local meridian'.
Question 186-38 : A definition of a magnetic track angle is ?
The direction of a line referenced to magnetic north.
.magnetic track angle the angle measured in a clockwise direction between the track and magnetic north... the direction of the longitudinal axis of an aircraft referenced to magnetic north is the magnetic heading of the aircraft... the direction of the longitudinal axis of an aircraft referenced to compass north is the compass heading of the aircraft.
Question 186-39 : The main reason for the occurrence of seasons on earth is ?
The inclination of the earth axis with regard to the plane of the ecliptic.
Question 186-40 : The length of the apparent solar day varies continuously throughout a year. this is caused by ?
The tilt of the earth's axis and the elliptical orbit of the earth around the sun.
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